Ko'olau Guitar & Ukulele Company

Ko‘olau Guitar & ‘Ukulele, Inc.

Pono Guitar & ‘Ukulele

401 North Cane Street A-10

Wahiawa, Hawaii 96786

To: Ko‘olau and Pono Dealers

Re: Adjustable Truss Rod

As most customers and dealers know, our Pono tenor and baritone ukuleles have an adjustable two-way truss rod, designed to maintain a straight fingerboard. Our ‘ukulele truss rod is similar to most acoustic guitar truss rods, but obviously much shorter. The access adjusting nut is inside the soundhole, just below the end of the fingerboard. With a 5/32” or 4mm hex wrench inserted into the adjustment nut, slowly and in small increments, turn clockwise to cause what is known as a “reverse” warp, or a bow back (sometimes called the opposite of a ski slope). To accomplish the opposite fingerboard curvature, namely a warp (or the ski slope effect), turn the truss rod nut counter clockwise, allowing for more of a gap between the strings and the frets.

To check the correct adjustment, press down any string at both the first fret and at the same time, the 12^th fret. While both are fretted check for the amount of space, or gap between the bottom of the string and the top of the fret. This is to determine what is known as fingerboard or neck “relief.” If no gap is felt or seen then the neck is too tight and the rod must be turned counter clockwise, again, in small increments of approximately 1/8 turns until there is a noticeable gap when tapping down the string (again, still fretted at the 1^st and 12^th fret). The space between the bottom of the string and the top of the fret should not be more than 1/16^th to 1/32” or in metric measurements, 1 to 2 mm.

Please note that the natural flexibility of the neck and fingerboard will be affected by weather and humidity conditions. During dry conditions (either natural low humidity or air conditioning or heating systems) a neck will develop a reverse warp. In a humid environment the neck will warp with the ski slope effect. And these conditions may vary throughout different seasons of the year. After several years of aging and use, in most cases an acoustic guitar or ukulele will eventually “acclimate” to its environment and there will be less need for continual adjustments.

Also note how a two-way truss rod works. Whether turning clockwise or counter clockwise you will eventually have an area of the rod with no threads, and thus it will appear that turning the adjustment nut is not accomplishing a tightening or loosening. When you have reached this portion of the rod continue turning in the same direction. Eventually you will feel the nut begin to tighten again, causing the neck to either bow forward, or bow backward depending on which way you are turning the nut.

If on occasion the adjustment is very difficult to turn, or seems to be frozen, do not force the adjustment. In rare cases the rod threads may be damaged, and the instrument must be returned for repair.

If you have any questions please feel free to contact us at any time.